Automatic system for supplying pulverized fuel to furnaces



E. v. FRANCIS 2,362,618 AUTOMATIC SYSTEM FOR SUPPLYiNG PULVERIZED FUELT0 FURNACES- Dec. '21, 1937.

Filed Jan. 23, 1935 s ShetQs-Shetl [NI/ENTOR: Ear/e M Franc/s ATT'Y.

Dc. 21, 1937. E. V.IFRANCISY 4 2,162,618 I AUTOMATIC-SYSTEM FORISUPPLYING PULVERIZED FUEL TO FURNACES Filed Jan. 23, 1933 5 sheets-sh-eem 2 //\/V.EN TOR: 47 far/e 1/ Francis ATT' Dec. 21, 937. v.FRANCIS 2,102,618

AUTOMATIC SYSTEM FOR SUPPLYING PULVERIZED FUEL TO FURNACES El M l6 weElg- 9 Ear/g l Hands,

INVENTOR:

ATTY Patented Dec. 21, 1937 l UNITED STAT PATENT "OFFICE" ration of OhioApplication'January 2a, 1933. Serial No. 652,975

, h h 2 Claims. My invention relates to automatic systems for Icontrolling the supply of pulverized fuel to furnaces and one of theobjects of the invention 'is the provision of improved and flicientthermostatically controlled apparatus for starting and stopping theoperation of a furnace and feedin a mixture of powdered coal and airthereto in accordance with temperature requirements.

A further object of the invention is the provision of improved ignitionmechanism associated with a nozzle for projecting a mixture of air andpulverulent combustible material into a furnace combustion chamber.

A further object of theinvention is the provision of an improved andefficient system of electrical control of the delivery of fuel to afurnace and providing safety'features for the em cient operation of thefurnace.

Another object of the invention is to provide a system for burningpulverized coal in a domestic furnace, in which a, preliminarycombustion chamber is provided within the main furnace combustionchamber which allows for free escape of ashes and hot gases ofcombustion. and in which combined gas and electric 'means is provided toignite the pulverized coal until said preliminary combustion chamber hasits interior walls heated to a temperature suflicient to supportcombustion of the pulverized coal. after which said ignition means'isshut off, while the pulverized coal is continued to be fed to said furvnace as dictated by thermostatic control means.

Other objects of the invention will appear hereinafter, the novelfeatures and combinations being set forth in the appended claimsReferring to the accompanying drawings, Fig. 1 is an elevational view ofan automatic thermostatically controlled heating system embodying myinvention; j

Fig. 2 is a sectional plan view of my improved preliminary combustionchamber with the fuel delivery nozzle and ignition mechanism connectedthereto and shown in plan view; 7

Fig. 3 is an enlarged sectional elevation (on line 3-3 of Fig. 2) of aportion 'of the structure shown in Fig. 2; v P

Fig. 4 is an enlarged plan view partlyin sectionv of the electric andgas ignition mechanism embodiedin the construction shown in Figs. 1 and2; V

Fig. 5 is a wiring diagram of the circuits and connections for theheating system shown in Fig. 1;

Fig. 6 is a wiring diagram with a modification; Fig. is an elevationalview of the switch panel lay for operating a motor control switch, and athermaltime limit cut-out switch.

Fig. 8 represents the position of the switches of Fig. 7 during thestarting period of the heating system;

Fig. 9 is a view similar to Fig. 8 but showing the position of theswitches during the running period; and h v Fig. 10 is a sectionalelevation of the thermostatic stack element for operating the switchesshown at the upper portion of Fig. 7.

In Fig. 1, l4 designates a furnace of thevertical type which may beeither in a hot air heating system, vapor heating system or steamheating system. While my improvements are particularly adapted to beinstalled in connection with a furnace alreadyin operation for theburning of coal in the ordinary way, it should be understood that mysystem may be permanently or detachably connected to a furnace wheninitially installed. The only changes necessary for the installation ofpreviously installed furnace are the removal of the usual fire grate andthe provision of suitable openings for the connections shown in Fig. 2.My improved preliminary combustion device i5 is mounted onverticaladjustable standards l6, l6 and comprises a supporting ring I!on which is mounted a cylindrical casing ill with a semispherical topvor cover I9 mounted" thereon as shown in Fig. 1. Rectangular sideopenings 20, are provided in the diametrically opposite sides of thepreliminary combustion device i5 and the walls of the latter are formedby sections of fire resisting material as shown at 2| in Figs. 1 and 2and at 22 in Fig. 1. v y

Secured to the bottom of the ring H at 23 adjacent the front portion ofthe furnace i4 is a flattenedpipe 24 which is provided with an upwardlyprojecting passage 25 to afford a nozzle. 28 for the mixture ofpulverized coal and air to be projected upwardly through the lowercircular opening in the bottom of the combustion device i5.

my.improved apparatus in connection with a The ignition apparatusassociated with the noz- 2 members 32 and 33. The forward end of therod- 80 screw-threaded into the contacting as shown in Fig.4, Theexposed terminal 31 ofthe rod 35 is located as shown in Fig.- 4 adjacentV the metal pin 38 which has one end embedded in insulated member 36with the other end extending to the center of the opening 39 to aposition adjacent the upper end' ofthe terminal 49. The latter as shownin Figs. 3 and 4 is mounted on the metal holder 42 which in turn issupported by the pipe 59. The lead 29 of the transformer 21 beinggrounded on the pipe 24 is in electrical connection with the terminal46' while the lead 28 is connected to the insulated terminal 31. Thereare, therefore, two spark gaps in series with each other, one beingrelatively short to produce a hot spark-while the other gap between theterminals 38 and 49 is relatively long to effect a flaming arc. When theprimary of the transformer is closed through the terminals 43, 43 a hotspark will be produced between the terminals 31, 38 and at the same timea flaming arc will be produced between the terminals 38. 40. Theterminals 31, 38, and 40 are composed of metal of a composition usual inspark plugs.

A gas supply pipe 44 is connected through a regulating valve 45 to theelectro-magnetically operated valve 46. The latter is connected by meansof the pipe 41 to the gas jet 48 which projects into the flaring mouth49 of the pipe 56, the latter being in communication with the chamherhaving opening 39 and the upwardly extending passage way 25 leading tothe nozzle 26. Air openings 5| are provided at the rear of the mouth 49as shown in Fig. 4. As hereinafter explained the electro-magnetic valve46 will be opened at the same time that-the ignition transformer 21 isoperated to produce the sparks between the terminals 31 and 38 andbetween the terminals 38 and 40.

If the electric ignition mechanism is omitted or is out of operation aconstantly burning gas pilot flame at 52 may be-relied on to ignite thegas flowing from the gas jet 48 when the electromagnetic valve 46 isopened. The pilot tube 53 is connected to a pilot regulating valve 54.The

pipe 53 is connected through the valve 54 to the supply pipe 44 inadvance of the regulating valve 45 so that the pilot flame may be cutoff without interfering with the operation of the electro-magnetic valve46.

The outer end of the flat pipe 24 is metallically connected to the metalconnector 55 and the latter is connected at its outer end to the pipe 56which leads to and is connected to the fan casing 51 of the pulverizedfuel feed mechanism 66.

The powdered fuel such as pulverized coal is adapted to be stored in thelarge bin 59 the lower end of which is conical or hopper shaped as shownat 69 in Fig. 1. The lower end of the hopper 60 is secured as shown inFig. 1 to a hopper shaped casting 62 of the pulverized fuel feedingmechanism 66 which is disclosed in detail in my divisional applicationSerial No. 727,270 flied May 24, 1934, said application being a divisionof my chute 83 is provided for delivering pulverized fuel' from thefeeding mechanism 66 to the fan in cas-' ing 51. Leveling screws H4 areprovided to level the base 63.

block 34 so as to electrically connect the rod 39 to another rod 35which is mounted in the in- 'An electric motor 89 mounted on the baseframe 63 has it armature shaft 99 connected by the coupling 9i to theshaft 92. Said shaft 92 drives the feeding mechanism 66 and also drivesthe fan in the casing 51 which fan delivers a mixture of pulverized fueland air to the pipe 56.

The stack switch device H8 is mounted on the flue II9 which leads fromthe furnace I4 as shown in Fig. 1. Fig. 7 shows the front of the ,stackswitch device H8 with the cover removed and Fig. 10 is a sectionalelevation of the upper portion of the stack switch device H8 includingthe stack switch element I20 which projects into the flue H9 to beheated thereby.

By referring to Fig. 5 it will be seen that when the room thermostatswitch I2I is moved to closed position while the main lineswitch I22 isclosed a circuit will be completed from the secondary winding I23 of thetransformer-relay I24 through the conductor I25, main pull-in mercuryswitch I26, conductor I21, auxiliary pull-in mercury switch I28,conductor I29, safety heating resistance I 39, conductor I3I, thermostatswitch I2I and conductor I32 to the other terminal of the secondary I23.

When the'main line switch I22 is closed a circuit is established fromthe main I33 through the conductor I34, lock-out mercury switch I35,conductor I35, primary winding I23, and conductor I38 to the other mainI332 I Fig. 7 shows that the secondary winding I23 of thetransformer-relay I24 acts as an electromagnetic winding for anelectro-magnet having a pole I36 adjacent to which is a movable armatureI36 which is pivoted to the frame of the electro-magnet and carries themotor mercury switch I31.

It will thus be seen that when the thermostat switch I2I closes thearmature I36 will be attracted to the pole I36 to effect closure of themercury switch I31. Thereupon a circuit will be established from theconductor I35 through the conductor I39, switch I31, conductors I49,

'I4I, motor 89, and conductors I42, I38 to the main I33.

At the same time that the motor circuit is closed a circuit will beestablished through the conductor I43, ignition mercury switch I44,conductor I45, and primary I46 of the ignition transformer '21, whichwill effect sparking between the terminals 31, 38 and 38, 40. I At thesame time that the motor is started and the electric ignition mechanismis operated a circuit is established through the conductor I49,electro-magnet 46, and conductor I59, to effect opening of the valve l5lfor passage of the gas through the gas supply pipe 44.

The closure of the thermostat switch I2I there- 'fore effects startingof the motor 89,0peration of the electric ignition mechanism and flow ofgas from the nozzle-48 shown in Fig. 4. When the motor starts, thefeeding mechanism shown in Fig. 1 operates to deliver amixture of airand powdered coal to the preliminary combustion device I5 for burningtherein preliminarily. the combustion being completed in the furnacechamber I52.

In some installations it is desirable to prolong the starting period andI have therefore mounted the auxiliary pull-in mercury switch I28 on thesame carrier I53 on which the hold-in mercury switch I54 is mounted. Asshown in Figs. 7 and 10 the carriers I53 and I55 are connected by springoperated frictional devices I56 and I51 on the rock shaft I58 the innerend of which is connected to the stack thermostat element I20. The I 26and I28 are closed can. sumcient current be adjustments are such thatwhen the combustion of the fuel begins, the heating in the flue II9 willbe suflicient to cause the thermostat element "I3I, thermostat switchHI, and conductor I32 to the other terminal of the secondary I23. The

resistance I60 is thus placed in series with the resistance I30 to cutdown the current through the latter sufllciently to prevent thelatterfrom .effecting operation of the tripping mechanism I63, and sumcientcurrent will flow through winding I23 'to maintain switch I31 closed.

. Asshown in Fig. 7 an expansion device I64 is located adjacent theheating resistance When sumcient current passes through the latter itwill heat to cause such expansion of the device I64 as to operate thetripping device I63 and "thereby permit the look-out mercury switch I35to tilt toopened position thereby cutting off the current from thesupply mains and necessitatvirigresetting by manually operating the knobI65.v By the arrangement of'the circuits shown in Fig. and theadjustments illustrated in Figs. '7. 8, and9. I have provided aprolonged starting period in such installations as require prolongedheating of the furnace,- before the stack element 5 I20 becomessufficiently heated to rotate the shaft.

I53 sufliciently to move the carrier I55 against the limit stop I66. Inother words, the time element for operation preliminarily of the heatingelement I30 to trip the switch I35 to opened position hasbeeneliminated. .When the furnace has been sumciently heated to move thecarrier I55-against the stoprl66 the main'pull-in switch I26 is openedand at the same time the ignition switch I44 is opened. whereupon theelectric ignition will discontinue in its operation and the valve I5Iwill close automatically. The-'motor 89 and the fan will continue inoperation how-- ever until a predetermined room temperature has beenreached, whereupon the thermostat switch I2I will be opened and thearmature I36 will move away from the pole I36 to open the motor switchI31, whereupon'the motor and fan will automatically stop and soalso thefuel feeding mechanism.

The thermostatic control switch comprises two pairs of contacts I 2I andI61 and when contacts I2I open in response to an increase inteinperature of the space to be heated, contacts I61 will be closed anda circuit will be established from a low voltage secondary I68 throughthe conductors I69, -I6I, hold-in. switch I54, conductor I62, resistanceI30,'conductor I3I, contacts I61 and conductor I to the other terminalof the secondary I68. The resistance I30 may be so proportioned that itwill act to operate the tripping mechanism. I63 if the stack element I20does not 0001 within a predetermined time to open the hold-in switchI54. During normal operation, however, within such predetermined closed.It should also be noted that an interval 'timethe hold-in switch I54will be opened and 'bothof the pull-in switches I26 and I28 will be willbe established before the closure of the thermostat I2I can restart thesupply of fuel to the furnace because not until both of the switchespassed to operate the armature I36. When the fuel supply has beenautomatically cut off by the opening of the thermostat I2Iv thepreliminary return of the carrier I53 against the stop "I will effectopening of the hold-in switch I54 and closure of the auxiliary pull-inswitch I28,

but the main pull-in switch I26 is still open and will remain open untilafter the shaft I58 has been rocked farther by further cooling of thestack element I20. When the carrier I55 reaches the stop I12 the mainpull-in switch I26 will be closed and the ignition switch I44 will heclosed in readiness for restarting when the. thermostat switch I2I isagain closed.

after a pre-determined length of time. For in-,

stance, if the stack element I20 does not rock the shaft I58 at allwithin a period of say 1% minutes the circuit through the resistance I30will cause the latter to effect the opening of the lock-out switch I35.

, In Fig. 6 under normal operations the preliminary rocking of the shaftI58 will cause the mer-' cury I14 in the device I13'to connect thecontacts I54 beforethe'switch I28 is opend. Therefore, the hold-inswitch I54 will be closed before the switch I28 is opened. The movementof the carrier I53 from the stop "I to the stop I50 will effect closureof the switch I54 and immediately afterward the opening of the switchI28. The resistance I60 will thereby be thrown into circuit with theresistance l 30 so as to prolong the starting period indefinitely oruntil the stack elements I20 has been heated sufliciently to move thecarrier I55 from the stop I12 to the stop, I66.

When this occurs the main pull-in switch I26 will be opened. Otherwisethe operation of the system illustrated in Fig. 6 is the same as thatillustrated in Fig. 5.. s

It should be understood that both in the system shown in Fig. '5 and thesystem shown. in Fig. 6 the secondary I23 is relatively high voltage andof sufllcient'strength to cause the armature I36 to move to the poleI36. The secondary I68 is, however, of relativelylow voltage and ofinsuflicient'strength to cause the armature I34" to move to the poleI36. The secondary I50 merely acts as the secondary. of a transformer toobtain the safety features above pointed out.

While in some furnaces a pulverized fuel burner may be provided withouthaving connected, thereto the preliminary combustion device I5, suchburner would require-continued burning of gas coal may be sufflcient tocause the same to be exttnguished if the gas flame from the' nozzle 26is not maintained. Therefgre'when the preliminary combustion device I5is omitted, I prefer to so arrange the electro-magnetic -valve structure46 as to be dependent on the motor switch I31 alone. This maybe done byplacing the electro-magnet of this valve structure in the motor circuitdirect-in the conductor I or In or I 38 shown in Fig. 6. Then the gaswill continue to burn at the nozzle 8 whenever the pulverized fuel burnsat the nozzle 26 and the fuel flame will not be extinguished but will bemaintained so long as the motor 89 operates the feedin mechanism and theblower.

However, it is highly desirable to reduce the 7 consumption of the gasand I therefore prefer to include the preliminary combustion device l sothat the gas may be cut oil? during the running period of the furnace.The refractory walls of the preliminary combustion chamber becomesufficiently heated during the starting period to act continuouslyduring the running period to maintain the pulverized fuel flame.- Forinstance, such refractory walls may reach a temperature during therunning period of approximately 2400 F. so that irrespective of thetemperature of the walls of the main furnace chamber I52 the burning ofthe fuelwill be maintained. Furthermore, the preliminary chamber l5confines the mix-- ture of the pulverized coal and air for ignition to alimited space without preventing gradual For instance, I have found byactual test of a practical heating system such as that disclosed herein,that the feed of the pulverized coal to the fan need be no greater thanone cubic foot in a period of twelve hours while burning of thepulverized coal in 'the furnace is being continuously sustained withoutthe burning ofany gas from the pipe 44 and the burner nozzle 48 duringthe running period.

Obviously those skilled in the art various changes'in the details andarrangement of parts without departing from the spirit and scope of theinvention as defined by the claims hereto appended, and I wish thereforenot to be restricted 'to the precise construction herein disclosed.

Having thus described and shown an embodiment of my invention what Idesire to secure by may make and contacts of a main switch which closein response to a determined lowering of the temperature of the space tobe heated, a second control circuit including a resistance and a thirdswitch in parallel with said first and second switches and in serieswith said heater, a third control circuit including said third switch,the resistance heater and the contacts of the main control switch whichclose in response to a determined rise in temperature of the space to beheated, and combustion responsive switching mechanism operable upon theestablishment of' bination with a furnace, of a fuel burning apparatuscomprising a power circuit and a control circuit, a safety cut-outswitch which when operated disables both of said circuits, fuel supplycontrol means in said power circuit, fuel ignition means in said powercircuit, a switch common to both 01' said means, a furnace heatresponsive switch individual to said ignition means, said controlcircuit comprising a series circuit including a room temperatureresponsive switch, a relay coil, a pair of furnace heat responsiveswitches and a time responsive operating means for said cut-out switch,a shunt circuit bridging said pair of furnace heat responsive switchescomprising a resistor and a furnace heat responsive switch, said roomtemperatureswitch being effective responsive to a predetermined minimumroom temperature to close its contacts and thereby close said seriescircuit whereby said relay coil and said time responsive operating meansare energized, means for closing said switch common to both said fuelsupply control'means and said fuel ignition means responsive to theenergization of said relay coil, said furnace heat responsive switch insaid shunt circuit operating responsive to an initial furnace heat toclose said shunt circuit, one of said pair of furnace heat responsiveswitches in said main series circuit operating responsive to an initialfurnace heat to open its contacts whereby the said series circuitincludes said shunt resistor which is effective to disable the operationof 'said time responsive operating means to prevent operation of saidcut-out'switch, said furnace heat responsive switch individual to saidignition means operating responsive to advanced furnace heat ,to disablesaid ignition means, and the other of said pair of furnace heatresponsive switches operating responsive to advanced furnace heat toopen its contacts, said switch-common to said fuel control means andsaid .fuel ignition means remaining under the control of said roomtemperature responsive switch. I

. EARLE V, FRANCIS.

